1. Field
This document relates to an electrostatic capacity type touch screen panel.
2. Related Art
In recent years, display devices such as a liquid crystal display, an electroluminescent display, and a plasma display panel having a quick response speed, low power consumption, and an excellent color reproduction rate, have been in the spotlight. The display device has been used for various electronic products such as a television, a monitor for a computer, a notebook computer, a mobile phone, a display unit of a refrigerator, a personal digital assistant, and an automated teller machine. In general, the display device interfaces with various input devices such as a keyboard, a mouse, and a digitizer. However, when a separate input device such as a keyboard, a mouse, etc. is used, a user is required to know how to use the separate input device and since the separate input device occupies space, use of the display device is inconvenient, making it difficult to increase the completeness of the product. Therefore, a request for a convenient and simple input device that can reduce an erroneous operation gradually increases. According to such a request a touch screen panel in which a user can input information by directly contacting with a screen by a finger or a pen is suggested.
Because the touch screen panel has a simple configuration while occurring little or no erroneous operations, can perform an input action without a separate input device, and has convenience in which the user can quickly and easily manipulate through contents displayed on a screen, the touch screen panel is applied to various display devices.
Touch screen panels are classified into a resistive type, a capacitive type, an electromagnetic type and so on according to a detection method of a touched portion. The resistive type touch screen panel determines a touched position by a voltage gradient according to resistance in a state that a DC voltage is applied to metal electrodes formed on an upper plate or a low plate. The capacitive type touch screen panel forms an equipotential with a conductive film and senses a touched position according to a difference in capacitance created in an upper or lower plate when the user touches the conductive film formed on the upper or lower plate. The electromagnetic type touch screen panel detects a touched portion by reading an LC value induced as an electromagnetic pen touches a conductive film.
Hereinafter, an electrostatic capacity type touch screen panel according to the related art will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan view illustrating an electrostatic capacity type touch screen panel according to the related art, and FIG. 2 is a cross-sectional view taken along line I-I′, line II-II′, and line III-III′ of the touch screen panel of FIG. 1.
Referring to FIGS. 1 and 2, the related art electrostatic capacity type touch screen panel comprises an electrode forming part A, a routing wire part B, and a pad part C.
The electrode forming part A is formed on a substrate 10 and comprises a plurality of first electrode serials Tx arranged in parallel in a first direction (for example, an X-axis direction) and a plurality of second electrode serials Rx arranged to intersect in a direction (for example, an Y-axis direction) perpendicular to the first electrode serials Tx. The first electrode serials Tx and the second electrode serials Rx cross over each other to sustain an electrical insulation state by an insulation layer 40. Each of the first electrode serials Tx comprises a plurality of first electrode patterns 50, and neighboring first electrode patterns 50 are connected to each other by a connection pattern 30. The connection pattern 30 is connected to the neighboring first electrode patterns 50 exposed through the insulation layer 40. Each of the second electrode serials Rx comprise a plurality of second electrode patterns 52 that are formed integral with each other.
The routing wire part B is formed outside the electrode forming part A, and comprises a plurality of first routing wires 22 connected to the plurality of first electrode serials Tx, respectively, and a plurality of second routing wires 24 connected to the plurality of second electrode serials Rx, respectively.
The pad part C comprises a plurality of first pads 26 connected to the plurality of first electrode serials Tx through the plurality of first routing wires 22, respectively, and a plurality of second pads 28 connected to the plurality of second electrodes 22 through the plurality of second routing wires 24, respectively.
Hereinafter, a method of manufacturing a related art electrostatic capacity type touch screen panel will be described with reference to FIGS. 3a to 6b. FIGS. 3a and 3b are cross-sectional views showing a first mask process of the touch screen panel of FIG. 1. FIGS. 4a and 4b are cross-sectional views showing a second mask process of the touch screen panel of FIG. 1. FIGS. 5a and 5b are cross-sectional views showing a third mask process of the touch screen panel of FIG. 1. FIGS. 6a and 6b are cross-sectional views showing a fourth mask process of the touch screen panel of FIG. 1.
Referring to FIGS. 3a and 3b, a first conductive layer is deposited on the entire substrate 10 comprising an electrode forming part A, a routing wire part B, and a pad part C through a deposition process such as a sputtering method. As the first conductive layer, a metal such as copper is generally used. After a photoresist is coated on the entire substrate 10 on which the first conductive layer is formed, and a first photoresist pattern for exposing the first conductive layer is formed in the routing wire part B and the pad part C by performing a photolithography process using a first mask. After removing the first conductive layer exposed by the first photoresist pattern through wet etching, lower layers 22a and 24a of the first and second routing wires are formed on the routing wiring part B, and lower layers 26a and 28a of the first and second pads are formed on the pad part C.
Referring to FIGS. 4a and 4b, a second conductive layer is deposited on the entire surface of the substrate 10 comprising the lower layers 22a and 24a of the first and second routing wires and the lower layers 36a and 26b of the first and second pad parts through a deposition process such as a sputtering method. As the second conductive layer, an indium tin oxide (ITO) layer is generally used. After a photoresist is coated on the entire substrate on which the second conductive layer is formed, a second photoresist pattern for exposing the second conductive layer is formed by performing a photolithography process using a second mask. After removing the first conductive layer exposed by the second photoresist pattern through wet etching, a plurality of connection patterns 30 arranged in parallel in a first direction (an X-axis direction) and separated from each other at a predetermined interval are formed on the electrode forming part A of the substrate 10, upper layers 22b and 24b of the first and second routing wires are formed on the routing wire part B respectively, and upper layers 26b and 28b of the first and second pads are formed on the pad part C respectively.
Referring to FIGS. 5a and 5b, after an insulation layer is formed on the substrate 10 in which the plurality of connection patterns 30, the upper layers 22b and 24b of the first and second routing wires, and the upper layers 26b and 28b of the first and second pad parts, first insulation patterns 40 are formed by patterning the insulation layer so as to expose both ends of each connection pattern 30 formed in the electrode forming part A by a photolithography process and an etching process using a third mask, and a second insulation pattern 42 is formed in the routing wire part B and the pad part C by patterning the insulation layer so as to expose the upper layers 26b and 28b of the first and second pad parts formed in the pad part C. The insulation layer comprises silicon nitride, silicon oxide, or organic resin.
Referring to FIGS. 6a and 6b, a third conductive layer is formed on the entire surface of the substrate where the first and second insulation patterns 40 and 42 are formed by a deposition process such as a sputtering method. As the third conductive layer, ITO may be used. After a photoresist is coated on the entire substrate on which the third conductive layer is formed, first electrode patterns 50 formed in parallel in a first direction (for example, an X-axis direction) and a plurality of second electrode patterns formed in parallel in a second direction (for example, an Y-axis direction) crossing over the first direction are formed in the electrode forming part A of the substrate 10 by performing a photolithography process and an etching process using a fourth mask, and uppermost layers 26c and 28c of the first and second pads are formed in the pad part C of the substrate 10. Each of the first electrode patterns 50 is formed so as to cover the ends of the connection pattern 30 exposed to the outside of the first insulation pattern 40. Thus, the neighboring first electrode patterns 50 are connected to each other by the connection pattern 30, thus forming a first electrode line Tx longitudinally extending in the first direction. Meanwhile, the second electrode patterns 52 are formed integral with each other so as to extend longitudinally in the second direction, thus forming a second electrode line Rx.
However, in the electrostatic capacity type touch screen panel according to the related art, for example, manufacturing processes are performed at a relatively low temperature (about 150° C.). Thus, the first electrode pattern 50 and the second electrode pattern 52 need to be kept thick in order to satisfy the surface resistance condition of the first electrode pattern 50 and second electrode pattern 52 that are touched. In this way, if the thickness of the first electrode pattern 50 and second electrode pattern 52 increases, the sputtering time for forming an ITO layer increases in order to form the first electrode pattern 50 and the second electrode pattern 52, and the etching time also increases. Therefore, the process yield is lowered. Especially, if the thickness of the ITO layer is too large, the residual film remains at the time of etching, thus making pattern formation impossible.